DSpace Community:http://dspace.cityu.edu.hk:80/handle/2031/715
Tue, 17 Feb 2015 03:22:32 GMT2015-02-17T03:22:32ZRethinking ventilation design for reducing airborne respiratory disease transmission in general hospital wardshttp://dspace.cityu.edu.hk:80/handle/2031/7003
Title: Rethinking ventilation design for reducing airborne respiratory disease transmission in general hospital wards
Authors: Yuen, Pak Leung (源柏樑)
Abstract: ﻿The widespread 2003 outbreak of SARS that claimed so many lives in Hong Kong was said to be due to hidden carriers responsible for spread of the disease to the community from public hospitals. SARS-infected patients with not yet recognizable and appreciable symptoms, so-called hidden spreaders, having been housed in general wards of hospitals, transmitted the disease unnoticeably. Precautions were subsequently taken because of the known likelihood of airborne transmission of SARS. However, at that time, isolation rooms that were set up in hospitals in regions and countries being attacked by SARS, such as Hong Kong, Singapore and Taiwan, were very much overwhelmed by the massive influx of patients with probable or suspected SARS. To accommodate the situation, some temporary makeshift ventilation modifications were identified and swiftly incorporated into general hospital wards to tackle the surge in patients. Indeed, this project study touched on the two key problem areas arising from the most recent SARS outbreak. These two industry problems have not yet received the necessary attention not to mention any resolution, and the study here is applying existing engineering knowledge in succinct and rigorous way to solve them with views to protect hospital occupants from airborne infectious disease attack.
The first problem is on "how to improve the isolation capability of existing general hospital wards to reduce the chance of cross infection due to hidden spreader". The second problem is on "how to make available a fast track sufficient quantity of isolation beds to meet patient surge in an infectious disease outbreak".
In addressing these two problems, this study focuses on identifying effective engineering control measures on indoor ventilation system design to minimize the spread of airborne respiratory diseases. The study adopts the proven methodology of computational fluid dynamics (CFD) analysis to simulate and compare the removal of microbes in a number of different hypothetical ventilation setups. The CFD approach was used to eliminate the risks of exposure to infectious pathogens that would occur in a real-life study.
In tackling the first question, the first objective of the thesis is to use CFD to verify a simple and cost-effective ventilation setup in a general ward by enhancing the ventilation air flow path and boosting up the air flow rate. This setting new was shown to match the CDC’s isolation facilities standard to restrict the spread of airborne infectious diseases in hospitals. This was a long-term solution for hospitals to upgrade their general ward ventilation systems. With these improvements, it is possible to match the standards maintained in a properly constructed isolation room but at a much lower cost. It is recommended that the newly identified ventilation parameters be widely adopted in the design of new general hospital wards to minimize cross-infection. Existing general hospital wards can be retrofitted at far less disruption and cost than would be incurred by full-scale refurbishment.
The second objective o this thesis is to use CFD to verify the fast-track, makeshift isolation setup of window mounted extract fans being incorporated during the 2003 SARS outbreak. It is a short-term, emergency approach and is recommended for hospitals to deal with patient surges in case of an airborne disease pandemic. When there is a shortage of isolation facilities to accommodate a pandemic surge in patients, the proposed ventilation setup should be added to existing general wards to minimize cross-infection, and these fans can simply be taken down after the surge.
In view of the great possibility of the emergence of new infectious diseases and of the ever increasing popularity of cross-country travel, the study of the ventilation setup in general hospital wards should not remain in its current state. These studies will help stopping the nosocomial transmission of infectious diseases by hidden spreaders at the verge of a disease outbreak, and also contain the massive isolation patient surge in case there is an outbreak.
Notes: CityU Call Number: RA969.4 .Y83 2012; 109 leaves : ill. 30 cm.; Thesis (Eng.D.)--City University of Hong Kong, 2012.; Includes bibliographical references (leaves [98]-104)Sun, 01 Jan 2012 00:00:00 GMThttp://dspace.cityu.edu.hk:80/handle/2031/70032012-01-01T00:00:00ZA new product concept formulation [framework] for the Hong Kong/Pearl River Delta consumable electronics and electrical products industryhttp://dspace.cityu.edu.hk:80/handle/2031/6995
Title: A new product concept formulation [framework] for the Hong Kong/Pearl River Delta consumable electronics and electrical products industry
Authors: Ho, Ka Nam (何稼楠)
Abstract: ﻿The current business environment in mainland China presents difficult challenges,
particularly for the electronic and electrical (EE) consumable product enterprises
located in the Hong Kong and Pearl River Delta (HK/PRD) region. Many EE
consumable product enterprises located in the HK/PRD region are facing difficulties
due to the increase on product complexity, ever-changing safety standards and
environment regulations. Furthermore, the enforcement of labour contract law, the
appreciation of the Renminbi, adjustments in processing trade policy etc., are all factors
that create further business difficulties. In such a critical environment, the EE
consumable product enterprises located in the HK/PRD region need to find ways to
maintain business.
The HK government and many industrial organisations suggested, the enterprises
should transform their business operations from Original Equipment Manufacturing
(OEM) to Original Design Manufacturing (ODM). It is because ODM is associated
with the development of higher value-added products. The suggestion arises from the
effects of keen local competition, especially the impact of product imitation and rapid
changes to product safety standards and environmental regulations for EE consumable
products. Switching business operations to ODM products can benefit enterprises by
helping them to remain internationally competitive and ensure their survival.
Although changing business operations is suggested as a means of survival, few
HK/PRD EE enterprises switched to ODM production. The top management of most
HK/PRD EE enterprises state that changing their style of operation is difficult. Some
of them argue that they have no experience in developing new products, and some point
out the lack of operational guidelines for execution and the high failure rate in NPD.
To reduce the failure rate and enhance the efficiency of NPD, most of the top
management on EE industry enterprises indicate the needs of a systematic NPD process.
Many NPD process models have been developed. These models begin with idea
generation and end with production and market launch. Most of them are designed
with a stage-gate structure, in which the gates represent the decision-making points.
Thus, the NPD process models provide a generic structure for enterprises only. As
stated by the industry's top management, the models do not include operational
guidelines for implementing the NPD process. Based on the necessity for a systematic
NPD process, especially the early development process (from idea generation to
preliminary assessment), this report develops a new product concept formulation framework and an NPD implementation roadmap, based on a two-phase NPD model.
The proposed two-phase NPD model simply divides the NPD process model into
two phases: the concept formulation phase and the product development phase. There
are gates throughout the proposed model; however, a consolidation gate is specifically
indicated between the two phases due to its importance on NPD decision-making.
Based on the above concept, a new product concept formulation framework is
developed. The new product concept formulation framework outlines a systematic
process for the first phase (concept formulation phase) of the proposed two-phase NPD
model. The framework specifies the steps in the NPD process and proposes a set of
NPD tools required for generating new ideas. The framework and the proposed NPD
tools enhance the efficiency of the NPD process by specifying a set of implementation
guidelines.
A roadmap for implementing the NPD process is required for enterprises that have
no experience of NPD. The roadmap outlines the steps for implementing the NPD
process, which starts with enhancing the awareness of NPD in the company. This is
followed by the preparation and planning stage. In this stage, responsible parties -
such as the top management, the NPD steering committee and the functional
department - prepare the task for implementation and plan its execution. After the
preparation and planning work, operational staffs undertake the tasks in the new product
concept formulation framework. When the new product concept formulation
framework operation is completed, the NPD steering committee reviews and, if
necessary, modifies the NPD process and the team structure.
The new product concept formulation framework, NPD implementation roadmap,
and the proposed NPD tools were developed and verified in a HK/PRD EE enterprise,
Techworld Industries Limited. The company was selected for implementation because
it wished to enhance its NPD process. A tailor-made, 21-step implementation roadmap
was developed for Techworld Industries Limited.
The NPD implementation roadmap has been executed in Techworld for 2 years.
Following the implementation, a questionnaire was distributed and the results are
summarised below. The interviewees agreed that the roadmap enhanced their
efficiency and effectiveness while working on the NPD process, because the
implementation roadmap and proposed NPD tools provided guidelines for execution.
An action plan was determined to guide the operational staff and enhance efficiency.
The proposed NPD tools are simple, thus allowing the NPD team to complete the
process of new product concept development. It allows top management to make decisions easily, as all of the necessary information is included. Finally, the success
rate in transforming new product ideas to the product development phase was enhanced.
The number of ideas that were selected for further development increased from one to
three, and one of these product ideas has been successfully launched on the market.
The results suggested the new product concept formulation framework facilitated the
execution of NPD in Techworld and enhanced the success rate of transforming new
product ideas into production or market launch. With the implementation of this new
product concept formulation framework, the company has benefited from the success of
a new product and enhanced the company's competence.
In this research, several significant are made: (1) early decision making enhance
the NPD efficiency and successful rate, (2) new product formulation framework and
implementation roadmap for HK/PRD EE industry is developed, and (3) four dominant
factors for HK/PRD EE industry are determined.
To conclude, a systematic NPD framework and implementation roadmap are established
for the HK/PRD EE industry. Such establishment helps the HK/PRD EE enterprises in
executing their business strategy to ODM production. A set of NPD tools are
established. The NPD tools are comparatively simple and user-friendly. The NPD
tools consist of sufficient information for top management's decision making.
Notes: CityU Call Number: HD9971.5.E543 C655 2012; xiii, 128, xxvii leaves : ill. 30 cm.; Thesis (Eng.D.)--City University of Hong Kong, 2012.; Includes bibliographical references (leaves 118-127)Sun, 01 Jan 2012 00:00:00 GMThttp://dspace.cityu.edu.hk:80/handle/2031/69952012-01-01T00:00:00ZAn investigation on broadband Internet service and its bill payment sentimenthttp://dspace.cityu.edu.hk:80/handle/2031/6991
Title: An investigation on broadband Internet service and its bill payment sentiment
Authors: Chan, Wai Chung (陳偉忠)
Abstract: ﻿The market of broadband Internet (BBI) service in Hong Kong has been saturated and fiercely
competitive. Most of the service providers formulate their strategies to cope with this
situation from the supply-side perspective. In order to address all the demand of consumers,
however, the marketers of the service providers should learn more about their consumers (the
demand-side) by considering the following questions.
(1) What service aspects of BBI service do most consumers concern about?
(2) Which service aspect in BBI service is the most influential one?
As bill payment was one of the top issues among consumer complaints, marketers should
address below questions as well.
(3) Does bill payment have impact on consumer sentiment towards whether to stay or quit
the current BBI service?
(4) How do consumers evaluate BBI service bill payment?
The aim of this dissertation is to address the questions listed above. To address these
questions, frameworks of consumer feeling towards BBI service, consumer sentiment towards
payment advice and the attributes of bill payment were developed in this research project.
Based on the frameworks, questionnaires were designed. Next, surveys were employed to
collect data from consumers. After data analysis, there were five major findings in response to
the above questions.
First, most consumers were concerned about four aspects of BBI service: bill payment, speed,
promotional offer and technical support service. These four BBI aspects were inter-related
and dictated by a model in terms of consumers' influential feelings. Second, bill payment was
the most influential BBI service aspect as found in the study. Third, a measure for assessing
consumer sentiment towards payment advice was established. With this measure, payment
advice of BBI service was found to have a significant impact on consumer sentiment as to
whether to stay with current service or not. Fourth, a set of evaluation criteria of bill payment
was established based on the consumer's preferred attributes of bill payment. Fifth, it was
found in illustration of evaluation criteria that the good features of the payment advice (e.g.
payment history shown) would have impacts on consumer's positive sentiment and that the
flaws of the payment advice (e.g. no service charge breakdown shown) would increase
consumer's negative sentiment or dissatisfaction.
Notes: CityU Call Number: HE7661 .C48 2012; 243 leaves : ill. 30 cm.; Thesis (Eng.D.)--City University of Hong Kong, 2012.; Includes bibliographical references (leaves 135-151)Sun, 01 Jan 2012 00:00:00 GMThttp://dspace.cityu.edu.hk:80/handle/2031/69912012-01-01T00:00:00ZBoundary slippage effect on hydrodynamic lubricationhttp://dspace.cityu.edu.hk:80/handle/2031/6654
Title: Boundary slippage effect on hydrodynamic lubrication
Authors: Yip, Lee Kei ( 葉莉姬)
Abstract: ﻿It is well aware that efficiency of machines and engines can be increased by
lubrication. Contact parts or components in relative motion in a well-lubricated
machine can be totally separated by a hydrodynamic lubricating film which prevents
direct solid contact and reduces friction. However, viscous friction still exists and its
magnitude is proportional to the viscosity of the lubricant. Simply speaking, using
thinner lubricating oil can reduce the magnitude of viscous friction, but it also reduces
the thickness of the lubricating film, i.e. lubricating effect is affected. Thus, the means
of using thinner oil to reduce lubricating friction is only limited and not practical.
Recently, an idea for reducing lubricating friction on the basis of boundary slippage
has been proposed. If the lubricant can slide on or move with a different speed of the
solid surface, friction can thus be reduced. To better use the boundary slip
phenomenon, this work aims to find out its effects on hydrodynamic lubrication for
various operation conditions through experimental and theoretical studies.
The experimental study started with a typical hydrodynamic system - squeeze
film. The set up included two horizontal parallel planes that were submerged in a
specimen lubricant. The lubricant was squeezed in the vertical direction. The load and
the corresponding relative displacement between two parallel planes were captured.
Experiments were carried out with various pairs of parallel planes. The lower plane
was fixed (untreated) while the upper plane was modified with different surface
treatments for various interfacial adhesion between the solid and the liquid. By
comparing the experimental measurements with the hydrodynamic lubrication theory
derived based on no-slip boundary conditions, genuine differences were obtained
which proved the existence of boundary slippery. Based on the experimental and
theoretical comparison, the degree of slip was inferred.
To more accurately and systemically capture the parametric effects on boundary
slip, shear film experiments were carried out with an optical slider test rig. The
hydrodynamic lubricating film was generated with a rotating transparent disc and a
stationary slider of adjustable tilted angles. The affinity of the specimen oil to the
bounding surfaces, as quantified with contact angle, was systematically varied by the amount surfactant added to the same base oil such that a wide range of contact angles,
from 3 to 52 degrees, was generated. The variation of film thickness against rotational
speeds and different loads were detected by optical interferometry, which provides
submicron measuring accuracy.
Comparing the experimental results of load and film thickness to the
hydrodynamic lubrication model with the critical shear stress criterion of slippage, the
degree of slip can be illustrated and the critical shear stress can be inferred. In squeeze
film experiments, the load carrying capacity was decreased with increasing the
contact angle. The critical shear stress, which was inferred from the comparison of the
experimental and theoretical results, was found having a negative effect on the
carrying load. Moreover, it was found the load carrying capacity varied linearly with
the squeeze velocity and this linear relationship was generally applied to specimen
oils of different interfacial affinity. In the slider test, the contact angle was found
increased with the amount of surfactant added. The experimental results illustrated
that the film thickness was decreased with increasing the contact angle for a given
load and speed. On the other hand, the increased contact angle would promote a
reduction in the critical shear stress as well as the work of adhesion. Hence, lowering
the wettability of an oil-solid system (larger contact angle) would promote slip, which,
in turn, reduces the film formation capacity. Moreover, it was found that the critical
shear stress is a linear function of shear rate. Lastly, the identified significant
parameters that affect boundary slippage include the contact angle (or wettability), the
critical shear stress, the shear rate, the speed and the work of adhesion.
Notes: CityU Call Number: TJ1073.5 .Y56 2011; xiv, 124, [18] leaves : ill. 30 cm.; Thesis (M.Phil.)--City University of Hong Kong, 2011.; Includes bibliographical references (leaves 119-124)Sat, 01 Jan 2011 00:00:00 GMThttp://dspace.cityu.edu.hk:80/handle/2031/66542011-01-01T00:00:00Z